BIOL 112 - 1st Edition Lecture20 Outline of Last Lecture I. Measurement of Blood VolumeII. Gas ExchangeIII. Respiratory SystemIV. Breathing (Ventilation)Outline of Current LectureV. Air ProcessingVI. VocalizationVII. Oxygen TransportVIII. CO2 ExchangeCurrent LectureI. Air Processing•Treatment process of air before gas exchange:•Warming: mostly in the nose, heat exchange•Humidifying: related to warming, mostly in nasal passages, water vapor content from 0.5% to 6%•Filtering: nose, trachea, bronchi, mucus traps dust and airborne microorganisms, ciliated epithelium sweeps mucus constantly to-ward epiglottis, mucus is swallowed and digested in stomach•Consequences of air processing failure:•Tracheostomy patients forced to breathe cold, dry air to have a much higher rate of lung infections and inflammationsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.•Smokers tend to lose epithelial function, excess of mucus stimu-lates the cough reflex (smoker’s hack)•Cough Reflex: epiglottis and vocal cords snap shut, abdominal muscles contract, epiglottis relaxes abruptly - - cough removes materials that epithelia can’thandle•All gasses exchanged mustpass through alveolar cells toenter or exit circulation (onlyexchange surface), alveolus isheavily vascularized•Respiratory Membrane:•Surfactant - 1 moleculethick, prevents alveolar col-lapse from surface tension(ex: dipalmitoylphophotidylcholine)•Extracellular fluid•Alveolar Epithelial Cell•Intercellular Space•Collagen around Capillary Cell•Capillary Cell•All gasses must be ex-changed by simple diffusion,NO ACTIVE TRANSPORT ofgasses across any surface,no facilitated diffusionII. Vocalization•Noise production•vocal cords in larynx•cords are thin sheets of muscle stretchedbetween arches of bone and muscles inlarynx•sound is produced tightening cord musclesand brings them into the air stream, cordsvibrate perpendicular to direction of air-flow•pitch and volume varied by varying forceand direction of cord movement, soundproduced is modulated by other parts ofrespiratory systemIII. Oxygen Transport•Hemoglobin - protein that carries oxygen in blood, a tetramer (4 polypeptides), can carry 4 oxygen molecules•Hemoglobin can carry much more oxygen pervolume of blood than by mere solution of oxy-gen in plasma.•Carried in erythrocytes because it is easier tomaintain high concentrations of mercury insuspension inside cells than by solution inplasma.•Oxygen Affinity Curve•S-shaped curve, the more O2 binds, thehigher the affinity for binding more, up tosaturationIV. CO2 Exchange•Unlike O2, CO2 is highly soluble and reacts with water•Rapid diffusion rate of CO2 permits quick removal from blood into alveolar air•In tissues, most CO2 is in the form of HCO3—•In lungs, CO2 is released as
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